Inkjet printer and method for forming an auxiliary layer based on medium type

An image forming method for an inkjet printer,

• said inkjet printer comprising an image-forming part that forms an auxiliary layer on a base material by ejecting droplets of an auxiliary ink toward said base material and forms an image on said auxiliary layer by ejecting droplets of an image-forming ink toward said base material, said auxiliary ink changing a dot formation state of droplets of said image-forming ink, and said base material being paper;
• said image forming method comprising the steps of:
• a) preparing a reference table that associates each of a plurality of basis weights of base materials and each of a plurality of types of base materials with a proper dot area rate to be used when forming said auxiliary layer, wherein said proper dot area rate is a dot area rate for forming said auxiliary layer where droplets of said image-forming ink are fixed to form dots of a certain size, and said dot area rate is a dot occupancy rate in an area of predetermined size;
• b) determining a dot area rate to be used when forming said auxiliary layer on a target base material on which an image is to be formed, as an auxiliary ink dot area rate, by referencing said reference table using a type and a basis weight of said target base material;
• and
• c) with said image-forming part, forming said auxiliary layer on said target base material in accordance with said auxiliary ink dot area rate and forming an image with said image-forming ink on said auxiliary layer.